Polyblend gems and the like and methods for producing them

ABSTRACT

Artificial gems are produced from matrix-type filaments comprised of a polyamide matrix-forming polymer having micronsized polyester fibrils dispersed in said matrix. The polymers have different indexes of refraction so that a cat&#39;&#39;s eye or chatoyancy effect is displayed when these filaments are fused together, shaped and polished.

United States Patent Robert C. Wincklhofer;

Gene C Weedon. both of Richmond. Va. 725.767

May 1, l968 June l, 197] Allied Chemical Corporation New York, N.Y.

lnvcntors Appl. No. Filed Patented Assignec POLYBLEND GEMS AND THE LlKEAND METHODS FOR PRODUCING THEM 4 Claims, 5 Drawing Figs.

US. Cl 63/32, 161/5, 161/19. 350/96 Int. Cl ..A44c 17/00, GOZb 5/14FieldotSearch 161/1,5,

Primary Examiner-John T. Goolkasian Assistant ExaminerLorraine T.Kendell Attorneys-Francis W. Guay and Roy H. Massengill ABSTRACT:Artificial gems are produced from matrix-type filaments comprised of apolyamide matrix-fonning polymer having micron-sized polyester fibrilsdispersed in said matrix. The polymers have different indexes ofrefraction so that a cat's eye or chatoyancy effect is displayed whenthese filaments are fused together, shaped and polished.

PATENTED JUN 11% 3.581.522

FIG. I FIG. 2

FIG. 3 FIG. 4

INVENTORS:

ROBERT C. WINCKLHOFEIR GENE. C. WEEDON ATTORNEY POLYBLEND GEMS AND THELIKE AND METHODS FOR PRODUCING THEM BACKGROUND OF THE INVENTION 1. Fieldof the Invention The present invention relates to a gem and othersimilar objects and to the methods of making them from polyblend fibersmade from at least two different polymers having different indices ofrefraction and different melting temperatures, with the higher meltingtemperature material present as small fibrils dispersed in a matrix ofthe lower melting point polymer. In order to make the gems an otherornamental objects, the filaments are fused together in a mass andformed to the desired shape. After polishing, the resulting article hasa silky sheen if the fibers are fused together in a random fashion, achatoyant sheen if the fibers are fused together in an aligned fashion,and shaped similar to a cabachon and exhibit astcrism if the fibers arealigned parallel to the side of a hexagon or other polygon prior tofusion.

v 2. Description of the Prior art Heretofore, gems and similarornamental objects have been made by taking thin, sheetlike pieces ofurea-formaldehyde broken into small pieces and mixing them with granulesof a synthetic resin such as methyl methacrylate, for example, andmolding this mixture under sufficient heating pressure to plasticize thesynthetic resin without plasticizing the pieces of solids. Also, priorto this invention, gems and similar omamental objects have been madefrom clear polymers having suspended therein birefringent material.Patents showing this prior art as well as other examples are Conner U.S.Pat. No. 2,353,995 and Boone U.S. Pat. No.2,663,l71.

SUMMARY OF THE INVENTION In accordance with the present invention, aunique new article having ornamental value, especially in thepreparation of gems, and the method for producing such an article hasbeen made. The starting material for making the article is a polymerfilament of the type shown in Twilley U.S. Pat. No. 3,369,057 issued onFeb. I3, 1968. The teachings in this patent are incorporated herein byreference and show afilament made from two different polymers, one ofwhich forms a matrix having a lower melting point than fibrils of adifferent polymer distributed throughout the filament and having theprincipal axis of the fibrils oriented primarily parallel to the axis ofthe filaments. The fibrils, which may be a polyester as shown in theTwilley patent, also have a different index of refraction than the nylonmatrix shown in the Twilley patent.

A large number of these filaments are oriented substantially parallel toone another either by winding on a mandrel or pulling through a die andusing suitable heat and pressure to the extend necessary to cause thefilaments to fuse to one another at the fusion point of the matrixwithout the orientation of the fibrils being destroyed. These fibrils,incidentally, have an order of magnitude approximating that of visiblelight. For example, the filaments of the Twilley patent have fibrilswhose average diameter is usually not above 1 micron and preferably notabove 0.5 microns, although the length on the average is at least 5times and usually at least times longer than the average diameter andtypically average a length of 250 times the average diameter. This is tobe contrasted with the wavelengths of visible light which extend fromabout 0.4 microns for the extreme violet to 0.72 microns for the deepred. By taking a section of these fused filaments and grinding andpolishing them into a hemispherical shape, called a cabachon bylapidaries, with the filaments and fibrils oriented substantiallyparallel to the base, an article is formed which will pick up andreflect light in a manner to afford a single streak referred to as catseye or chatoyancy in certain natural gems which exhibit a similarphenomenon. While the exact scientific explanation for this phenomenonis not know, it is theorized, without being bound thereby, that thechatoyancy is due to the fibrils being oriented primarily in a singledirection acting as transparent or translucent inclusions with adifferent index of refraction than the transparent matrix, with thediameter being of the order of magnitude of the wavelength of light,whereas the length is substantially longer than the wavelength of light.If we are not talking about quantum effects, there is no such thing as aray" of light. A ray simply represents the direction along which part ofa wave front is advancing. An analysis of the behavior of light as anelectromagnetic wave shows that the fundamental processes of refraction,reflection and scattering between two interfacing materials havingdifferent indices of refraction'are not at all simple when one of thematerials has a dimension of this order of magnitude and when adjacentfibrils may be spaced at comparable dimensions. Instead of bouncing offthe interface between the two media, a wave train actually penetratesthe second medium for a short distance before turning back into 'theoriginal material. Light conduction lengthwise of the fibrils comes toresemble the transmission of microwaves by wave guides with most of theenergy traveling down the fibril along the outside rather than insidethe fibril in such a manner that a single streak of light perpendicularto the direction of the fibrils manifests itself in a cabachon-cut.

Also, ornamental surfaces can be prepared using this material in anonoriented manner to display a silky sheen with numerous reflections.This is useful and moldable in itself as a new ornamental article eventhough it does not have the dramatic effect of the cats eye.

If the filaments before being fused are laid in a manner that they areparallel to the sides of a square, hexagon or octagonal prism, thenasterism with four, six or eight points on the star will be manifested.Similarly, other polygonal shapes such as a pentagonal prism may be usedto create a five'pointed star.

Also, the ornamental object produced can merely be used as one componentin producing a gem or other object which is made up of several layersutilizing other materials therewith. Also, the fineness and the depth ofthe cats eye can be con trolled by the quantity and alignment of theoriginal fibrils or by dissolving out some of the fibrils aftermanufacture.

The jewelry and other objects produced using this material can take onmany forms such as cuff links tiepins, buttons, decorative ornaments,decorative coatings, and so forth.

Many objects and advantages of the present invention will becomeapparent from the following description taken in conjunction with theaccompanying drawings:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partial sectional view ofthe mandrel upon which the filament is wound;

FIG. 2 is a view of'FIG. 1 after the filament has been wound thereon;

FIG. 3 is a perspective view of a cube cut from the wound filament ofFIG. 2 and mounted on a top;

FIG. 4 is a side view of the material of FIG. 3 after it has been groundto a hemispherical shape; and

FIG. 5 is a plan view of FIG. 4 after the hemisphere has been polishedto show the cats eye.

DESCRIPTION OF THE INVENTION As a first example of the practice of theinvention, a filament composed of a polyblend of 70 percent nylon 6 and30 percent of a polyester is extruded and drawn in accordance with theteachings of the Twilley patent with a drawn denier of 840. Thisfilament is then twisted into a yarn to have a denier of 840 and iswound onto an aluminum mandrel in the form of a sheave 8 inches indiameter having a cross section such as shown in FIG. 1. The depth ofthe groove is one-half inch, the width of the groove at the bottom isone-half inch and the width at the top is three-fourths inch. The yarnis wound onto the sheave by mounting the sheave onto the shaft of avariable speed motor and wrapping 3 to 4 yards of yarn about the centralgroove in order to tighten the yarn onto the sheave. The sheave is thenrotated by adjusting the motor settings so that as the yarn is fed intothe groove the yarn is slightly overlapped on each successive completerotation of the sheave. The yarn is wrapped under suitable tension toprevent yarn slippage. When the sheave groove is completely filled withyarn, additional winding is confined to the center portion of the grooveso that about three-sixteenth inch of wrapped yarn extends beyond theedge of the sheave shown in FIG. 2. It is unnecessary to tie the end ofthe yarn to any support member since static electric charges built upduring winding hold the cut end onto the wound bundle. The wound yarn isfused together at a temperature above the melting point of nylon 6 andbelow the melting point of the polyester which is polyethyleneterephthalate. A temperature of 250 C. has been found to be suitable.The time required for fusion depends upon the size and construction ofthe sheave, its material of construction and the yarn denier. In theexample just given, the fusion took place between 30 to 90 minutesexposure at 250 C. by heating in an oven. The fusion could also beeffected by use of other heat sources such as infrared lamps and thelike. During heating the nylon matrix does not melt and flow as might beexpected, but rather is fused into a cohesive mass. During this fusionprocess the alignment of the polyester particles is not substantiallyaffected. The net result is a solid yar'n bundle having fibrils widelydispersed therein which are aligned substantially parallel to oneanother around the annular yarn bundle. The wound sheave is removed fromthe oven and cooled to a room temperature by quenching the assembly inwater. Tilting in an airstream could likewise be used, as well as othermeans of cooling. The fused yarn is then cut from the sheave by sawingacross the yarn bundle.

A cube five-eighths inch on a side is then cut from this fused yarn andthe side which corresponded to the top layer or outside surface of theyarn is roughened with sandpaper and glued to a -inch round wooden dopusing a commercial glue manufactured by Borden Chemical Company known asElmer's Glue. The assembly is then allowed to dry for 16 hours and, asshown in FIG. 3, the fibrils run parallel to the left bottom mounted onthe dop. The edges of the cube are rounded by pressing the cube againsta rotating sanding disc preparatory to mounting the dop in a metallathe. After mounting in the lathe, the rounded cube is cut into ahemispherical shape. The

rough-cut shape is subsequently polished by mounting the assembly in arotary drill and rotating the assembly at l,700 rpm. The material ispolished by successive sandings with 50, 100, 200, 300 and 400 gritsandpaper with final polishing being accomplished by crocus cloth togive the final shape as shown in FIG. 4. The polished assembly is thenplaced in boiling water for 30 minutes to facilitate the removal of thehemisphere from the-dop as the Elmers Glue is softened by the hot water.The finished piece is yellow-ivory in color and exhibits a bright,flashing line perpendicular to the direction of the yarn windings asshown in FIG. 5. Gem cuts of this kind with rounded smooth surfaces arereferred to as cabachons.

A second example may be carried out following the procedures set forthfor example 1, except utilizing a yarn made from 204 filaments twistedinto a 1,260 denier yarn. The resulting cabachon gem is identical tothat produced by the first example except the cats eye is slightlybroader. This is believed to be due to the fact that the thicker deniermade by the Twilley process produced fibrils slightly larger and givesrise to the observation that the finer the denier of the startingfilament, the finer the line observed in the finished product.

A third example for practicing the invention is to produce a gem by thefirst example and then remove part of the polyethylene terephthalatefrom the fused yarn by exposure to a 5 percent solution of sodiumhydroxide at 100 C. for 48 hours followed by water extraction inajacketed soxhlet for 36 HOURS. This procedure removed 80 to 85 percentof the total amount of polyethylene terephthalate from the original yarnand produced a lustrous gem having a greater depth to the cats eye.

A fourth'example of carrying out the invention may be accomplished byusing a yarn extruded and drawn from 75 percent nylon 6 and 25 percentpolyethylene terephthalate mix ture with the filament count being 14twisted into a yarn of 210 denier and fused in an oven at 220 C. for 45minutes. This would produce a cats eye having a narrow line of light.

As a fifth example, the yarn of example I is chopped into short lengthsand compressed between two matched dies made from aluminum to form therough outline of the hemispherical cabachon as shown in FIG. 4. Acompressed material is then heated at 250 C. for 45 minutes in an oven,after which it is removed and cooled by a water quench. The roughhemisphere is glued to the dop, then sanded and polished in the mannerof example I. The finished piece is yellow-ivory but does no exhibit thebright, flashing line characteristic of chatoyant or cats eye gems. Thisis unquestionably due to the fact that the fibrils are no longeroriented in one principal direction but instead have a randomorientation which gives rise to the silky or milky lustre of the gem.

As a sixth example, a gem is prepared by making a hexagonal prism fromthe fused yarn bundle prepared in accordance with the first example. Sixtriangular prisms fiveeighths inch in height and one-half inch on eachside of the triangle are cut from the bundle in such a manner that thefibrils run substantially parallel to one side of the prism, which shallbe referred to as the base side, and intersect the other two sides at asubstantial angle. The fibrils also run substantially parallel to thetop and bottom of the prism. These six prisms are joined together in theform of a hexagonal prism fiveeights inch high by placing the sixmembers together so that the base side to which the fibrils runsubstantially parallel forms the six outer sides of the prism. These sixsmall triangular prisms are then autogenuously fused together by placingthem under pressure sufficient to hold the sides together in the form ofthe hexagonal prism while raising the temperature to 250 C. for minutes.The fused mass is then water quenched, mounted on a dop with the base ofthe prism being the surface glued to the dop and ground to the shape ofa hemispherical cabachon in the same manner set forth in the firstexample. The resulting gem exhibited asterism by displaying severalcross streaks to produce a six-pointed star.

As a seventh example, a fused ring is prepared as in example 1, exceptthat the groove in the aluminum mandrel is threefourths inch deep inorder to provide a greater depth to the fused ring. After the yarn iswound and fused but prior to being cut from the sheave, l2 equally flatsections are milled 0n the outer circumference with each of the sectionsbeing 2 inch long. The fused ring is then cut from the sheave along aradial plane passing through the line where the flat faces intersect.Following this, the remainder of the ring is divided by cutting along aradial plane which intersects the line connecting the remaining flatsectors. The cylindrical inner portion is then ground flat in a planeparalleling the previously cut flat plane. From this blank are cut sixtriangular prisms one-half inch in height and five-eighths inch on eachof the three sides with the aligned axis of the yarn running parallel tothe base of the prism and parallel to one of the sides but intersectingthe other two sides at a substantial angle. These six sections are gluedtogether into a hexagonal prism using Eastman 910 Adhesive manufacturedand sold by the Eastman Kodak Company of Rochester, New York. Thisadhesive is a methyl 2 cyanoacrylate. The hexagonal prism is formed fromthe triangle in a manner that the filaments run parallel to the base andto the sides. The assembly is then mounted onto a large wooden dop usingElmers Glue and cut into the form of a hemispherical cabachon. Again, asix-pointed star with each point having a line running through themiddle of the original triangular section is displayed.

As an eighth example, the process of the immediately preceding exampleis repeated except each triangular section is immersed in formic acidfor 30 minutes. The formic acid penetrates the outer surface of thesection, softening the nylon without disintegrating the fused yarn. Thetriangular sections are assembled as before using a circular clamp tohold them in position. The assembly is allowed to dry overnight. Finalremoval of the formic acid is accomplished by drying the clamped pieces8 hours under vacuum at 80 C. The clamp is removed and the hexagon issecured to a wooden dop as previously described and a hemisphericalcabachon is made therefrom. The resulting gem resembles the previouslydescribed gem except the lines formed between the cut edges are finerand less noticeable. An additional advantage of this technique is thatthe adhesive in this gem is dyed to exactly the same depth and shade asthe original material.

As a ninth example, the process of example eight is repeated except thetriangular prisms have two of their sides meeting at a 72 angle with thetwo remaining angles each being 54. The side bounded by the 54 angles isthe one to which the filaments are oriented in parallel planes. Five ofthese triangles are joined together to make a pentagonal prism with theresulting gem exhibiting a five-pointed star. Using the same technique,three-pointed, seven-pointed, and other odd-numbered points of stars canbe fon'ned, something never achieved in nature.

As a example, example 1 is repeated except the fibers are bundledparallel to one another rather than wound about a mandrel and sufficientcircumferential pressure is applied thereto to cause them to jointogether as a fused rod when heated to the melting point of the nylon.Gems cut from this material are similar to those of example I, exceptdue to difficulties in fiber alignment, the cats eye is broader than inthe case of the filaments having more perfect alignment as a result ofbeing wound on the mandrel.

As an ll example, example 1 is repeated but using a mandrel that has agroove with one flat side and the other side forming a series of six%-inch steps. Each step is in the form of a hexagonal prism one-eighthinch high with each step varying in the base dimension from the bottomportion which is mounted on a its-inch mandrel to the outer dimensionwhich is approximately 2 inches along the greatest dimension of thehexagon. The yam' is then fused in an oven at 250 C. for 3 hours, Theyarn used is the same as in example 1 except the filament count is 136wound into a yarn of 840 denier. After fusing the cohesive mass isremoved by the disassembly of the mandrel so as to provide a shellapproximately one-fourth inch thick whose outer surface is ground andpolished and a small gem otherwise prepared placed in the /4-inchmandrel hole. The resulting cabachon is almost 2 inches in diameter atits base and dramatically displays a six-pointed star.

As a 12 example, example I is repeated except only one of the filamentsin the yarn is a polyblend filament of nylon and polyester, theremaining filaments being pure nylon. The resulting gem displays a catseye having a greater depth than that of the first example.

The gems and other ornamental objects produced by the above examples canbe formed in a infinite variety of colors by using the usual dyeingtechniques for the various polymers either when they are in the yarnform prior to being used or else by dyeing or coating subsequent to themanufacture of the finished product. Also, numerous other polymer blendsmay be utilized provided they can be presented in the form of filamentshaving fine fibrils dispersed in a transparent or translucent matrixwhich polymer fibrils have a higher melting point and a different indexof refraction than the matrix polymer. It was theorized above that thelight-modifying properties of the article are believed to be due to thesmall diameter of the fibrils and their having a different index ofrefraction than the matrix; however, it may be additionally theorizedthat the interface between the filaments where they have been fused toone another may also give rise in varying degrees to the lightmodifyingproperties provided by the articles made in the above examples.

The fibrils should be present in the matrix in substantial quantitieswith a diameter not greater than three times the wavelength of visiblelight, that is less than about 2.5 microns and, preferably, asubstantial quantity of the fibrils should have a diameter less than thewavelength of visible light of O.72 microns. These fibrils should be atleast 5 microns long.

It IS not necessary that the materials prepared in accordance with theexamples herein be furnished merely in the form of hemisphericalcabachons, as other cuts may be utilized or flat, round objects withholes for buttons or flat objects combined with other light-affectingmembers of infinite variety can be produced utilizing the principles ofthis invention which discloses methods and objects giving rise to newpossibilities in light-modifying materials. Also, it will be apparentthat still other modifications of the materials and products and methodsabove described may be made in following the general principlesexemplified herein. Therefore, such examples as have been presented areto be regarded as merely illustrative and the invention may be otherwiseembodied and practiced without departing from the nature and spirit ofthe invention and it is to be understood that the invention is notlimited to the details set forth herein except as set forth in theappended claims.

What l claim is:

1. An artificial gem comprised of light-transmitting matrix filamentsfused together, said filaments being comprised of a polyamide matrixhaving polyester fibrils dispersed generally parallel in said matrix,said fibrils having a diameter of less than about 2.5 microns and alength greater than about 5 microns in substantial quantity to provide adifferential index of refraction.

2. The article of claim 1 in the shape of a cabachon with the surfacepolished and the fibrils generally parallel to the cabachons base sothat rays of light are displayed.

3. The article of claim I in the shape of an asteriated gern displayinga star having an odd number of points.

4. The article of claim 1 in which the matrix polymer is polycaproamideand the fibrils are polyethylene terephthalate.

2. The article of claim 1 in the shape of a cabachon with the surfacepolished and the fibrils generally parallel to the cabachon''s base sothat rays of light are displayed.
 3. The article of claim 1 in the shapeof an asteriated gem displaying a star having an odd number of points.4. The article of claim 1 in which the matrix polymer is polycaproamideand the fibrils are polyethylene terephthalate.